Coreless flexible film packaging system and coreless containment package therefor

ABSTRACT

A coreless flexible film packaging system is disclosed. The system includes: (i) a containment cylinder including a cylindrical wall defining first and second cylinder end apertures and an interior film containment area; (ii) a film feed slot in the cylindrical wall extending longitudinally along the containment cylinder; and (iii) a supply of flexible film wound about itself to form a film roll having a central cylindrical cavity, said roll including a leading end and a terminal end and contained within the interior film containment area. A coreless containment package and a method for packaging a flexible film are also described.

FIELD OF THE INVENTION

The present invention relates to packaged flexible polymer films andpackaging systems for flexible polymer films.

BACKGROUND OF THE INVENTION

In the prior art, flexible films formed from polymeric materials and/orplastics are typically packaged at the manufacturing site as rolls, withthe film wound onto a cylindrical supporting carrier formed from rigid,non-compressible plastic, cardboard or the like (called a core). Theroll is then enclosed and contained in a box, bag or other packaging toprotect the film during transport and provide an aesthetically pleasingappearance to customers. For some products, for example films forapplication to windows installed in automobiles and buildings, theflexible films are often packaged during manufacture in large and heavy“bulk” rolls; however, product distribution channel requirements demandthat film wound on such bulk rolls be unwound and then rewound intosmaller “commercial” rolls for shipping and eventual sale. By way ofexample, such window films are often wound on bulk rolls of around 3000meters at manufacture and then repackaged for sale to customers inrelatively short rolls wherein 30.5 meters or less of material is woundon a 76.5 mm diameter plastic core. Highly specialized flexible films,such as metallized films for use in medical testing devices, electronicdevices, displays and the like, are also packaged as rolls of materialwound on a core.

So that the film can be wound onto the core properly for commercialrolls, the leading end of the film nearest the core is typically adheredto the core using a double-sided self-adhesive strip that runstransversely along the full width of the film at the leading end. Whenthe film is unwound from the commercial roll for use, the 1-3 meters ofthe film packaged nearest the core when originally wound thereon, isoften found to be unusable as a result of a repeating imprint, sometimesreferred to as an “embossment”, created in the initial wraps of the filmaround the core. Because the flexible film is relatively thin, in theorder of 60-400μ, this imprint effect is replicated in several of theinnermost layers of wound film close to the core. These imprints arecaused by one or more factors typically present in the packaging processand system. There are several reasons why film suffers from imprints.These include:

Film tension. Mechanical requirements demand that tension is appliedduring winding in order to be able to process film through the windingmachine.

Film Edge. The leading end of the film runs across the width of thewound film and is cut with a relatively sharp vertical edge that forms aridge at the interface of the film's leading end with surface of thecore.

Adhesive Strip. The double sided adhesive strip has a minimized(typically 25-50μ) but nonetheless potentially impactful thickness andcan create an even more severe imprint than the end of the film. Itpresents two ends rather than one and the general evenness of thethickness of adhesive strip over the entire area of adhesive,particularly hand-applied aerosol pressure sensitive adhesives, can bevery poor.

Core surface. The core surface itself may have defects or minutecontaminants that impact its uniformity and smoothness.

These imprints are typically permanent such that, if use of the film isattempted, defects in the final product's functionality and/or aestheticappearance are highly likely. With respect to window films, installationof this portion of the film from the roll on a vehicle or buildingwindow is often the source for consumer complaints and warranty claims.

One prior art attempt to overcome the embossment problem includedchamfering the leading end of the film so that the cut end of the filmis angled or gradually reduced in thickness rather than presenting asharp vertical end. It is difficult with such thin materials, however,to achieve any uniform angled cut of this kind, particularly at such ashallow angle as would be necessary to materially reduce the impact ofthe leading end on the imprint problem. Other prior art methods toreduce imprinting involve changing aspects of the core, for example (i)milling an angled depression into the length of the core such that theleading end of the film seats in the depression in the core so as topresent a smooth surface over which subsequent layers of film wrapduring winding onto the core or (ii) modifying the core to include aslit or other feature to “trap” and/or hold the leading end of the filmwithin the core cavity. Such solutions are, however, typically not costeffective as they add expensive machining, molding, slitting or otherhigh-precision steps to the core manufacturing process and create theneed for cores that are highly customized to match individual film typesand thicknesses. Further, they also present challenges in properlyadhering the leading end of the film to the core so that the roll can beproperly wound.

Despite these prior art efforts, embossments remain a significant sourceof waste and inefficiency for the flexible films industry. Aside andapart from the embossment problem, the films industry is in lock stepwith industry in general as it seeks out improved, sustainable packagingsystems and for its products that reduce excess packaging material andwaste.

SUMMARY OF THE INVENTION

In a first aspect, the present invention relates to a coreless flexiblefilm packaging system. The system includes (i) a containment cylinderincluding a cylindrical wall defining first and second cylinder endapertures and an interior film containment area; (ii) a film feed slotin the cylindrical wall extending longitudinally along the containmentcylinder; and (iii) a supply of flexible film wound about itself to forma film roll having a central cylindrical cavity, with the rollcomprising a leading end and a terminal end and contained within saidinterior film containment area.

In another aspect, the present invention further relates to a corelesscontainment package for containing a supply of flexible film comprisinga leading end and a terminal end and wound about itself to form a filmroll. The package includes (i) a containment cylinder for containing thefilm roll, with the containment cylinder including a cylindrical wallwith an outer surface and the cylindrical wall defining first and secondcylinder end apertures; and (ii) a film feed slot in the cylindricalwall extending longitudinally along said containment cylinder.

In yet another aspect, the present invention relates to a method forpackaging a flexible film including: (i) providing a containmentcylinder, the cylinder including a cylindrical wall and a film feed slotextending longitudinally along the containment cylinder, with thecylindrical wall defining first and second cylinder end apertures and aninterior film containment area; (ii) feeding the flexible film into theinterior film containment area through the film feed slot; and (iii)winding said flexible film about itself to form a film roll having acentral cylindrical cavity lined by the film, with roll contained withinthe interior film containment area.

Further aspects of the invention are as disclosed and claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an embodiment of the corelessflexible film packaging system of the present invention, with thepackaged flexible film shown partially outside the containment cylinderfor illustration purposes only.

FIG. 2 is partial side elevational view of an embodiment of the corelessflexible film packaging system of the present invention, with thepackaged flexible film shown partially outside the containment cylinderfor illustration purposes only.

FIG. 3 is a partial side elevational view of an embodiment of thecoreless containment package of the present invention.

FIG. 4 is a side elevational view of an embodiment of the corelesscontainment package of the present invention that includes caps.

FIG. 5 is a partial side elevational view illustrating suitableequipment for practicing the method of the present invention forpackaging a flexible film.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, a first aspect of the present invention isdirected to a coreless containment package 10 for containing a supply offlexible film 15. The film 15 includes a leading end 18 and a terminalend 19 and is wound about itself to form a film roll 20 which includes acentral cylindrical cavity 25 that is preferably lined by film 15. Thecoreless containment package 10 includes containment cylinder 30 forcontaining the film roll 20. The cylinder 30 includes cylindrical wall35 having an outer surface 40, with cylindrical wall 35 defining firstand second cylinder end apertures 45 and 50. Containment package 10further includes a film feed slot 55 in said cylindrical wall 35extending longitudinally along the containment cylinder 30. Containmentcylinder 30 may be formed from materials well known to one of ordinaryskill, for example cardboard or plastics such as polypropylene orpolystyrene, using well-known manufacturing techniques selecteddepending in part on the material chosen, such as for example injectionmolding or hot melt extrusion when the core is formed from plastic. Theterm “coreless” is utilized herein to denote that the film is woundabout itself to form a film roll which includes a central cylindricalcavity lined by film as opposed to packaging in which the film roll iswound onto a cylindrical supporting carrier or core.

As shown in FIGS. 3 and 4, the coreless containment package 10 of thepresent invention preferably further includes seal strip 57 affixed tosaid containment cylinder 30 at said outer surface 40. Preferably theseal strip 57 is located adjacent to film feed slot 55 and mostpreferably is also affixed to the terminal end 19 of the supply of saidflexible film 15. Seal strip 57 may be applied to the core and formed insitu from materials well known to one of ordinary skill, for example apressure sensitive, hot melt or curable adhesive. Seal strip 57 may alsobe a separately formed adhesive tape adhered to the core.

In a particularly preferred embodiment, the coreless containment package10 further includes caps 60 at each of said first and second endapertures 45 and 50. Caps 60 may be formed from materials well known toone of ordinary skill, for example thermoplastic polymers, usingwell-known manufacturing techniques such as for example injectionmolding and hot-press molding. In this embodiment, the outer surface 40of the cylindrical wall 35 of the cylinder constitutes the exposedsurface of a coreless flexible film packaging system as described below.In comparison to the prior art flexible film packaging systems whereinfilm wound on a core formed from rigid, non-compressible plastic,cardboard or the like which is then contained in a box, bag or otherpackaging to protect the film, this embodiment of the present inventionprovides an advantageous, environmentally friendly and cost-savingalternative system that uses significantly less packaging material andaccordingly reduced packaging waste. In this embodiment, at least one ofthe caps 60 is substantially transparent so as to facilitate visualinspection of the film. Outer surface 40 may also optionally include atleast one of printing or graphics so as to provide information and/or anaesthetically pleasing appearance to customers.

In a second and related aspect, the present invention relates to acoreless flexible film packaging system. In its most general sense andas shown in FIGS. 1-4, the coreless flexible film packaging system 75 ofthe present invention includes flexible film 15 contained withincoreless containment package 10. Accordingly, the coreless flexible filmpackaging system 75 includes: (i) a containment cylinder 30 thatincludes cylindrical wall 35 having an outer surface 40, withcylindrical wall 35 defining first and second cylinder end apertures 45and 50 and an interior film containment area 52; (ii) a film feed slot55 in said cylindrical wall 35 extending longitudinally along saidcontainment cylinder 30; and (iii) a supply of flexible film 15 woundabout itself to form a film roll 20 having a central cylindrical cavity25 lined by film 15. Film 15 further includes a leading end 18 andterminal end 19 and is contained within said interior film containmentarea 52. Containment cylinder 30 may be formed from materials well knownto one of ordinary skill, for example cardboard or plastics such aspolypropylene and made using well-known manufacturing techniquesselected depending in part on the material chosen, such as for exampleinjection molding or hot melt extrusion when the core is formed fromplastic.

The system 75 preferably further includes seal strip 57 affixed to saidcontainment cylinder 30 at said outer surface 40. Preferably the sealstrip 57 is located adjacent to film feed slot 55 and most preferably isalso affixed to the terminal end 19 of the supply of said flexible film15. Seal strip 57 may be applied to the core and formed in situ frommaterials well known to one of ordinary skill, for example a pressuresensitive, hot melt or curable adhesive composition. Seal strip 57 mayalso be a separately formed adhesive tape adhered to the core.

In a particularly preferred embodiment, the system 75 further includescaps 60 at each of said first and second end apertures 45 and 50. Caps60 may be formed from materials well known to one of ordinary skill, forexample thermoplastic polymers, using well-known manufacturingtechniques such as for example injection molding and extrusion. In thisembodiment, the outer surface 40 of the cylindrical wall 35 of thecylinder constitutes the exposed surface 80 of the coreless flexiblefilm packaging system. In comparison to the prior art flexible filmpackaging systems wherein film is wound on a core which is then enclosedin a box, bag or other packaging to protect the film, the system 75provides an advantageous, environmentally friendly and cost-savingalternative that uses significantly less packaging material andaccordingly reduces the amount of packaging waste. Further, it will bereadily appreciated that the film feed slot of the system is also adispensing port for the contained flexible film in this embodiment.

In this embodiment, at least one of the caps 60 is substantiallytransparent so as to facilitate visual inspection of the film. Exposedsurface 80 may also optionally include at least one of printing orgraphics so as to provide information and/or an aesthetically pleasingappearance to customers.

The flexible film for use with the present invention may be any flexiblefilm, web or the like typically packaged concurrent with or aftermanufacturing as a roll. Non-limiting examples include PET,polypropylene, PVC, polyurethane and the like. Preferably, the flexiblefilm is “self-winding”, defined herein to encompass films that exhibit anatural tendency to wind or curl about themselves without application ofexternal force. For example, many films utilized in the window filmsindustry develop during manufacture what is known in the art as “MD(machine direction) curl”, a tendency of the film to curl in thedirection in which the film travels during process operations such asdyeing, coating, laminating and slitting. This tendency can beparticularly relevant in flexible films with multiple laminated layersor applied coatings and is created as tension that is applied during theprocessing steps elongates the film and creates strain in the layersthat varies for example by layer type and thickness. For example, MDcurl in commercial window film constructions generally towards thescratch-resistant coating.

In a third aspect, the present invention relates to a method forpackaging a flexible film. The method of the present invention includes:(i) providing a containment cylinder that includes a cylindrical wallwith an outer surface and a longitudinally extending film feed slot,with the cylindrical wall defining first and second cylinder endapertures and an interior film containment area; (ii) feeding theflexible film into the interior film containment area through the filmfeed slot; and (iii) winding said flexible film about itself to form aroll having a central cylindrical cavity lined by said film, with theroll contained within the interior film containment area.

Suitable equipment for operation of the method of the present inventionis shown in FIG. 5. With regard to the in-feed step, film may be fedinto the film containment area of the containment cylinder by means of afeed device such as a driven nip roller 65 in relatively close proximityto the film feed slot 55. The containment cylinder is preferably heldstationary in position during the feeding step. It will be understood byone of ordinary skill that a number of variables, such as for examplethe feed velocity and feed angle of the film on entry into thecontainment cylinder, through the feed slot and the distance between thenip and the feed slot may be adjusted to optimize winding performance.It is anticipated that film angled towards the top inside surface of thecore and the shortest distance from the nip to core entrance slot willprovide better winding.

Preferably, the flexible film is a self-winding film which winds aboutitself to form the roll without externally applied force and the windingstep therefore includes self-winding of the flexible film. For example,in the embodiment where the flexible film is a window film that includesa scratch-resistant coating, winding would include self-winding of theflexible film toward the scratch resistant side. In typical window filmconstructions, this will leave a release liner side, a more slipperysurface, to slide against the inside surface of the cylinder duringwinding.

Optionally, the winding step may include applying external winding forceto the film. In one particular embodiment, the optional winding force isapplied by a rotatable axle 85 such that the winding step of the methodpresent invention includes (a) removably inserting a rotating axle 85into the interior film containment area 52 and (b) removably attachingsaid leading end 18 of flexible film 15 to the axle 85. In thisembodiment, the method of the present invention most preferably includesthe further step (c) of releasing the leading end of the film from theaxle at the conclusion of said winding step and removing the rotatingaxle from interior film containment area. In a particularly preferredembodiment, rotating axle 85 is a perforated axle connected to avacuum/pressure source such that the removably attaching step (b) abovepreferably includes applying vacuum to the flexible film during windingand the releasing step (c) preferably includes releasing the vacuum whenwinding is complete. The releasing step (c) may optionally also includeapplying positive pressure to the flexible film to facilitate release ofthe leading end of the flexible film 15 at the conclusion of the windingstep when winding is complete. Axle 85 and the nip roller speed shouldbe controlled and adjusted so that the flexible film 15 does not wind uparound the axle 85 but is simply held by it at and close to the leadingend 18.

As movement of materials such as flexible films can cause static buildup, it will be understood that the method of the present inventionpreferably includes electrically grounding the flexible film and thecontainment cylinder.

The foregoing description of various embodiments of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the preciseembodiments disclosed. Numerous modifications or variations are possiblein light of the above teachings. The embodiments discussed were chosenand described to provide the best illustration of the principles of theinvention and its practical application to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

That which is claimed is:
 1. A coreless flexible film packaging system,said system comprising: (i) a containment cylinder comprising acylindrical wall with an outer surface, said cylindrical wall definingfirst and second cylinder end apertures and an interior film containmentarea; (ii) a film feed slot in said cylindrical wall extendinglongitudinally along said containment cylinder; and (iii) a supply offlexible film wound about itself to form a film roll having a centralcylindrical cavity, said film roll comprising a leading end and aterminal end and contained within said interior film containment area.2. The coreless flexible film packaging system of claim 1 wherein saidflexible film is self-winding.
 3. The coreless flexible film packagingsystem of claim 1 wherein said central cylindrical cavity is lined bysaid film.
 4. The coreless flexible film packaging system of claim 1further comprising a seal strip affixed to said containment cylinder atsaid outer surface.
 5. The coreless flexible film packaging system ofclaim 4 wherein said seal strip is adjacent to said film feed slot. 6.The coreless flexible film packaging system of claim 4 wherein saidterminal end of said supply of said flexible film is affixed to saidseal strip.
 7. The coreless flexible film packaging system of claim 1further comprising caps at each of said first and second end apertures.8. The coreless flexible film packaging system of claim 7 wherein atleast one if said caps is substantially transparent.
 9. A corelesscontainment package for containing a supply of flexible film comprisinga leading end and a terminal end and wound about itself to form a filmroll having a central cylindrical cavity, said package comprising: (i) acontainment cylinder for containing said film roll, said cylindercomprising a cylindrical wall with an outer surface, said cylindricalwall defining first and second cylinder end apertures; and (ii) a filmfeed slot in said cylindrical wall extending longitudinally along saidcontainment cylinder.
 10. The coreless containment package of claim 9further comprising a seal strip affixed to said containment cylinder atsaid outer surface.
 11. The coreless containment package of claim 10wherein said seal strip is adjacent to said film feed slot.
 12. Thecoreless containment package of claim 10 wherein said terminal end ofsaid supply of said flexible film is affixed to said seal strip.
 13. Thecoreless containment package of claim 9 further comprising caps at eachof said first and second end apertures.
 14. The coreless containmentpackage of claim 13 wherein at least one of said caps is substantiallytransparent.
 15. The coreless containment package of claim 9 whereinsaid central cylindrical cavity is lined by said film.
 16. A method forpackaging a flexible film, said method comprising: (i) providing acontainment cylinder, said cylinder comprising a cylindrical wall withan outer surface and a film feed slot in said cylindrical wall extendinglongitudinally along said containment cylinder, said cylindrical walldefining first and second cylinder end apertures and an interior filmcontainment area; (ii) feeding said flexible film into said interiorfilm containment area through said film feed slot; and (iii) windingsaid flexible film about itself to form a roll having a centralcylindrical cavity lined by said film, said roll contained within saidinterior film containment area.
 17. The method of claim 16 wherein saidwinding step includes (a) removably inserting a rotating perforated axleinto said interior film containment area; and (b) removably attachingsaid leading end of said flexible film to said axle.
 18. The method ofclaim 17 wherein said removably attaching step (b) includes applyingvacuum to said flexible film.
 19. The method of claim 17 furthercomprising releasing said vacuum and optionally applying pressure tosaid flexible film at the conclusion of said winding step.
 20. Themethod of claim 17 further comprising removing said perforated axle fromsaid interior film containment area at the conclusion of said windingstep.